Film, its production method, and polarizer and liquid crystal display device using the film

A film containing a cellulose acylate, a hindered amine compound at least 0.001% by mass relative to the cellulose acylate, and a plasticizer, satisfying: (i) the concentration C1 of the hindered amine compound 3 μm from the first film surface is higher than the concentration C2 3 μm from the second film surface; (ii) the concentration A of the plasticizer 3 μm from the first film surface is lower than the concentration B 10 μm from the first film surface; (iiia) the 15 acyl substitution degree a of the cellulose acylate 3 μm from the first film surface is lower than the acyl substitution degree b 10 μm from the first film surface; and (iiib) the 20 weight-average molecular weight Ma of the cellulose acylate 3 μm from the first film surface is higher than the weight-average molecular weight Mb 10 μm from the first film surface.